Dolphins are
active predators and eat a wide variety of fishes, squids, and
crustaceans such as shrimps. The foods available
to a dolphin vary with its geographic location (Barros and
Odell, 1990).
B. Food intake.
Adult bottlenose dolphins eat approximately
4% to 5% of their body weight in food per day. A nursing
mother's daily
intake is considerably higher: about 8% (Cockcroft
and Ross, 1990).
A dolphin's stomach is compartmentalized
for rapid
digestion. It can also function as a crop when
food is taken opportunistically.
C. Methods of collecting
food.
Feeding behavior is flexible and adapted
to a dolphin's particular habitat and available
food
resources.
Dolphins do not chew their food.
Usually they swallow fish whole, head
first, so the
spines
of the fish won't
catch in
their throats. They break larger fish
by shaking them or rubbing them on the
ocean
floor.
Hunting strategies are varied and
diverse. a. Bottlenose dolphins often cooperate
when hunting and catching fish.
(1) In open waters, a dolphin pod sometimes
encircles a large school
of fish and herds them into a
small, dense
mass, sometimes
using their tail flukes
to stun the fish. The dolphins take turns
charging
through
the school
to feed.
(2) Occasionally
dolphins herd schools of fish
against a sand
bar or shoreline
to trap
them
in shallow water
where they are
easy prey (Shane, et
al., 1986).
b. Dolphins also feed
on individual,
nonschooling fishes (Shane, 1990)
c. To hunt larger
fishes, a bottlenose
dolphin
may use its tail
flukes to kick
a fish out
of the water,
then retrieve
the stunned prey
(Shane, 1990).
d. Bottlenose
dolphins often
feed in association
with
fishing operations.
Dolphins in
Texas bays frequently
accompany shrimp
boats. They
feed on fishes
that are caught
incidentally
in
trawl nets intended
for shrimps
(Fertl and
Wursig, 1993).
A pod of dolphins sometimes encircles a school of fish and herds
them into a tight ball for feeding.
